PB2004: CHRONIC MYELOMONOCYTIC LEUKEMIA AND CONCOMITANT MONOCLONAL GAMMOPATHY: A MULTICENTRE RETROSPECTIVE STUDY OF CLINICAL CHARACTERISTICS, PREVALENCE AND OUTCOME
Authors: Elisa Diral, Gregorio Maria Bergonzi, Elena Elli, Fabrizio Cavalca, Stefano Crippa, Lorenzo Rizzo, Marta Riva, Fabio Ciceri, Massimo Stefano Luca Bernardi
Journal: HemaSphere (2023)

Topic: 10. Myelodysplastic syndromes - Clinical Background: Chronic Myelomonocytic Leukemia (CMML) is a rare hematologic malignancy at risk to progress to secondary acute myeloid leukemia (AML). Few patients are reported in the literature to have both CMML and plasma cell disease, mostly Multiple Myeloma; furthermore, no data about concomitant detection and significance of monoclonal gammopathy of undefined significance (MGUS) are available. Aims: We retrospectively conducted an analysis of patients affected by CMML, prospectively diagnosed at three hematological centres to study the incidence and characteristics of MGUS, and the correlation with outcomes. Methods: Data from 84 consecutive CMML patients, diagnosed according to the WHO 2016 criteria between 1995 and 2022, were evaluated. Data about clinical, morphological and hematological features of CMML patients and type of treatment were collected retrospectively. The CMML-specific prognostic score system (CPSS) was used to define the prognosis of all patients. Time to progression in AML and overall survival (OS) were determined from CMML diagnosis to the LAM evolution and to death or last contact, respectively. Results: The median age at diagnosis was 73 years (range 19 - 90), 57 patients were males (68%) and 27 females (32%). According to WHO 2016 classification we identified 35 (42%) myelodysplastic CMML and 49 (58%) myeloproliferative CMML; 39 (46.4%) patients were classified as CMML-0, 29 (34.6%) as CMML-1 and 16 as (19.1%) CMML-2. CPSS risk score was low in 24 (28.6%), intermediate-1 in 26 (30.9%), intermediate-2 in 25 (29.8%), and high in 8 (9.5%) patients, respectively. Most cases (n= 68, 80.9%) were oligoblastic forms (blasts < 5% in peripheral blood and < 10% in bone marrow). According to treatment, 10 (11.9%) patients received hypomethylating agents (5-azacitidine), 19 (22.6%) hydroxyurea, 17 (20.2%) allogeneic haematopoietic stem cell transplantation as upfront or consolidation therapy, 32 (38.1%) patients did not receive any treatment. Progression to AML occurred in 23 (27.4%) cases. At last follow up, 36 (42.9%) patients were alive; the median overall survival of the entire cohort was 20 months (range 0.8 – 329). Concomitant MGUS was detected in 18 (21.4%) of 82 evaluable patients: 11 (61.1%) were males, 7 (38.9%) females; all patients were older than 60. 9 patients (50%) were CMML-0, 4 (22.2%) CMML-1 and 5 (27.8%) CMML-2, with a prevalence of oligoblastic forms in 72.2% of cases; CPSS was low/intermediate-1 in 11 (61.1%) and intermediate-2/high in 7 (38.9%) cases respectively. Summary/Conclusion: In our cohort of CMML patients, concomitant MGUS was detected in one-fifth of patients, with about two-third of cases occurring in oligoblastic forms and lower CPSS risk classes. No difference in terms of AML progression or impact on survival was evidenced. Our data suggest that MGUS may occur frequently in patients with lower risk CMML without impact on disease outcome; further analyses will be needed to confirm this observation.Keywords: CMML, Myeloid malignancies, MGUS, Chronic myelomonocytic leukemia